PiXtend eIO Hardware Manual
Connection Notes
The following circuit diagram illustrates the connection of analog current sensors to the
analogue current inputs of PiXtend eIO Analog One.
The measuring current flows through a shunt resistor with a value of 20 Ω. So if a voltage
transmitter is connected to the output, the maximum permissible measuring current of 20
mA flows even at very low voltages:
U
max
= 20 Ω * 20 mA = 0.4 V
If larger voltages are applied to the input, the current flow increases rapidly over the
permitted range and is limited at approx. 100 - 150 mA by a self-resetting fuse.
Even if this avoids defects, it is not recommended to let the input currents increase
permanently or in normal operation above 20 mA.
Currents greater than 20.65 mA can not be evaluated in the software.
The ground connections (GND) of external power supplies must be connected directly to
the GND terminals on the terminal strips near the analog inputs.
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Figure 44: Principle circuit diagram: connection of the analog current inputs
